Damaging winds in the Keweenaw Friday evening, July 1st

Gusty straight-line winds on the leading edge of of a decaying line of thunderstorms resulted in wind damage across portions of the Keweenaw Peninsula Friday night, July 1st.

Many locations across the northern half of Houghton County and Keweenaw County experienced brief wind gusts in the 45 to 50 mph range as the thunderstorms moved into the area between 11:15 PM and Midnight EDT. There were some areas of localized stronger winds which resulted in damage to structures and trees.

The National Weather Service in Marquette conducted a ground survey of storm damage in and around the Calumet area and confirmed that the enhanced damage in Calumet was the result of a microburst or localized significant straight-line winds. Within Calumet, there was a corridor of heavier damage from near Red Jacket Road east-northeastward across Caledonia Street where numerous trees were uprooted or snapped, several outbuildings were significantly damaged, and roof damage occurred to several structures. While most of the damage was consistent with 65 to 70 mph wind gusts, where the more significant damage occurred suggested winds gusts were in the 80-85 mph range.

Additional wind damage occurred in Keweenaw County. Over 100 trees were blown down between Delaware and Copper Harbor and along M-26 between Eagle Harbor and Copper Harbor.

Figure 1 -- National Weather Service Doppler Radar Reflectivity Image from Marquette at 1125 pm EDT -- The line of thundestoms moving across the Keweenaw Peninsula with the strongest winds along the leading edge of the precipitation. (click on the picture to zoom in)

Figure 2 -- National Weather Service Doppler Radar Reflectivity Image from Marquette at 1148 pm EDT -- The weakening line of thunderstorms 20 minues later as it appraoched Copper Harbor. (click on the picture to zoom in)

Photographs of some of the storm damage in and around the Calumet area. Click on any photograph for a larger image. (photos courtesy of Dale Plant and NWS Storm Survey Team)